bcc/tools: Replace bpf_probe_read with bpf_probe_read_kernel

It is recommended to use bpf_probe_read_kernel_{str} in the bpf tools.
See kernel commit 0ebeea8ca8a4 ("bpf: Restrict bpf_probe_read{, str}()
only to archs where they work")

Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
diff --git a/tools/nfsslower.py b/tools/nfsslower.py
index 5e344b9..6b94f34 100755
--- a/tools/nfsslower.py
+++ b/tools/nfsslower.py
@@ -190,18 +190,18 @@
     struct qstr qs = {};
     if(type == TRACE_GETATTR)
     {
-        bpf_probe_read(&de,sizeof(de), &valp->d);
+        bpf_probe_read_kernel(&de,sizeof(de), &valp->d);
     }
     else
     {
-        bpf_probe_read(&de, sizeof(de), &valp->fp->f_path.dentry);
+        bpf_probe_read_kernel(&de, sizeof(de), &valp->fp->f_path.dentry);
     }
 
-    bpf_probe_read(&qs, sizeof(qs), (void *)&de->d_name);
+    bpf_probe_read_kernel(&qs, sizeof(qs), (void *)&de->d_name);
     if (qs.len == 0)
         return 0;
 
-    bpf_probe_read(&data.file, sizeof(data.file), (void *)qs.name);
+    bpf_probe_read_kernel(&data.file, sizeof(data.file), (void *)qs.name);
     // output
     events.perf_submit(ctx, &data, sizeof(data));
     return 0;